Perforator for well casing



Nov. 20, 1962 M. E. TRUE PERFORATOR FOR WELL CASING Filed 091;. 16, 1958 "ilnited @rates 3,064,571 PERFORATOR FOR WELL CASENG Martin E. True, Houston, Tex., assigner, by mesne assignrnents, to Jersey Production Research Company, Tulsa, Ghia., a corporation of Delaware Filed ct. 16, 1953, Ser. No. 757,664 9 Claims. (Cl. IGZ-21.3)

The present invention is directed to -a perforator for perforating well casing and the like. More particularly, the invention is directed to a gun perforator which is useful in perforating a well casing without perforating an adjacent pipe therein. In its more specific aspects, the invention is concerned with a perforator provided with positioning means.

The present invention may be briey described as a perforator for perforating-casing and the like which comprises an elongated cylindrical body member adapted to be lowered through a first pipe in the casing to a position adjacent a second pipe in the casing, the pipes being arranged eccentrically in the casing. The elongated body member is provided with perforating means and with a positioning arm arranged in an elongated recess formed in the body member. The positioning arm has a length sufficient to extend out of the recess a distance greater than the greatest distance between the second pipe and inner wall of the casing. Spring means are provided which bear against the arm and the body member which is of sufficient strength for urging .the arm out of the recess and positioning the body member against the casing; and frangible releasing means are also provided for maintaining the arm in the recess. Perforating means is carried by the body member opposite the positioning arm such that on release of said positioning arm the perforating means is oriented to erforate only the casing Without perforating the second p1pe.

The perforating means employed in the present invention is suitably a bullet gun or shaped charge or a plurality of bullet guns or shaped charges. While it is preferred to employ a shaped charge as the perforating means, other perforating means such as chemical perforating means and mechanical perforating means may be used.

The positioning arm has a length such that, when it is extended, the extended length is greater than the greatest distance between the second pipe and the inner Wall of the casing. The positioning arm is provided with a trigger which serves to close a switch in an electric circuit connected to a source of electrical energy for operating the perforating means such as by firing same when it is a bullet gun or a shaped charge.

The releasable means is suitably a frangible means which may be an explosively operated shear pin and the like.

The present invention is suitably used in a well which has been drilled to penetrate a plurality of hydrocarbon productive zones, sands, horizons, strata, formations, and the like, from which it is desirable to obtain simultaneously hydrocarbons from several of said zones such as from an upper zone and a lower zone. Thus in such multiple completions, a plurality of pipe or tubing strings such as two or more may be eccentrically arranged in a well casing with one tubing string extending through an upper zone to a lower zone while another tubing string terminates with its lower end in or above the upper zone with the lower zone being separated from the upper Zone by a suitable packer and the casing-tubing annulus also being closed above the upper zone with another packer.

In the present invention either one or all of the several tubing strings are preferably arranged with their lower ends above a plurality of hydrocarbon productive strata such that the well may be worked over or recompleted employing the permanent well completion technique which has been adequately described in the patent literature. The present invention is useful and advantageous in such multiple completions inasmuch as in Working over or reperforating in an upper Zone, means are provided -for avoiding the perforation of the tubing extending through the upper zone; otherwise there is danger of the tubing string being perforated when the upper zone is perforated. By providing apparatus for perforating the casing where one pipe string is adjacent a zone to be perforated, the pres-ent invention is quite useful and irnportant.

The invention will be further illustrated by reference to the drawing in which a preferred embodiment is illustrated and in which:

FIG. l shows an arrangement of a well with the device of the present invention positioned for perforating an upper zone;

FlG. 2 is a cross-sectional view of FIG. 1 with the tubing gun lowered out of oneof the tubings adjacent a second tubing showing one position for perforating the casing;

FIG. 3 is a similar view to FIG. 2 showing a second position for perforating the casing; and

FIG. 4 is a partial sectional and enlarged view of the gun perforator of the present invention.

Referring nov to the drawing and first to FIG. l, numeral 11 designates a well bore drilled from the earths surface to penetrate a plurality of hydrocarbon productive strata, some of which are in the upper Zone 12 and the other of which may be in the lower zone 13. Arranged in the bore hole 11 is a casing 14 which is cemented in place with primary cement 15. A first tubing string 16 is arranged in the casing 14 and terminates with its lower end 16a above or in the upper zone 12. A second tubing string i7 which is parallel to the rst tubing string 16 extends through the upper zone 12 and terminates with its lower end 1S above or in the lower zone 13. The lower zone 13 is separated from the upper zone 12 .by a packer 19 while the casing-tubing annulus 2i! is closed by a second packer 2l.

Lowered through the tubing 16 and into upper zone 12 by means of a conductor cable 2.2 is the gun perforator 23 of the present invention Which is provided with a positioning arm 2e and perforating means 25, which, when operated, serves to perforate the casing 14, cement 15, and the upper Zone 12 to form the perforations 26.

Referring now to FIGS. 2 and 3, it will be seen that the casing 14 has the tubing 17 arranged therein with the perforator 23 and its positioning arrn 24 positioning the perforator such that when tired it perforates only the casing 14 Without perforating tubing 17, the positioning arm 24 having an extended length greater than the greatest distance between the tubing 17 and the inner wall of the casing 14. As shown in FIGS. l to 3 of the drawing, the positioning arm 24 in its fully extended position Orients the perforator 23 by slidable contact with the tubing 17.

It is to be noted that the perforating means 25 are carried by the body member opposite the positioning arm 24 such that the casing 14 only will be perforated Without penetrating the pipe string or tubing string 17.

Referring now to FIG. 4, the perforator 23 is provided with perforating means 25, which are illustrated in this embodiment as shaped charges but which may be bullet guns and is provided with a positioning arm 24 arranged in a recess 24a formed in the perforator 23. The positioning arm 24 is releasably held in place by a releasable means 27 bearing against the arm 24, which suitably is an explosive shear pin in the recess 24a, which, on being exploded, causes the arm 24 to be extended by an urging means such as spring 2S which bears against a retaining pin 28a with end 29 and against the arm 24 with end 30.

The shaped charges or perforating means 25 are iired by an electrical circuit connected to a source of electrical energy which may lead to the earths surface through the conductor cable 22, the electrical circuit having a safety switch 3d therein which is operated by an actuating trigger 32. which comes into operative engagement or contact with the switch 31 on being pivoted around a pivot 33 to extend the arm 24. As can be seen in FIG. 4 an electrical current may be sent through lead 34 to the open safety switch 31 and through lead 3S to ignite the explosive shear pin 27 where upon the arm 24 is released. The trigger 32 closes the safety switch 31 sending the electrical current through lead 35 to blasting cap 37 which ignites the prima cord 38 iiring the perforating means 25. This provides that the perforating means 25 will be operated or tired only when the arm 24 is in extended position such as shown in FIGS. 2 and 3 to allow perforating of the casing 14 without perforating the v'tubing 17.

From the description taken with the drawing, it will be clear that the perforating means 23 is free of any connection with the tubings 16 and 17 and is positioned Ysuch that the perforating means will be operated only when the periorating means is positioned to fire in a direction'away from the tubing 17. In order to assure that the perforator of the present invention is properly positioned before tiring, the conductor cable 22 may be manipulated up and down to be sure that the perforator 23 is rotated and assumes a position such as shown in FIGS, 2 and 3.

While the frangible releasing means has been shown as being released by a small explosive charge, it may be suitably released or ruptured by a force asserted from I the surface by means of the conductor cable 22; thus an upward pull on a shear pin releasing means with a su'icient force to rupture same may be sufcient to release the positioning arm 24. Under some circumstances, the frangible releasing means may be dispensed with. For example, a perforator of this type omitting the releasing means may be positioned in a tubing by manually holding the positioning arm in a collapsed position in the recess and thus inserted in the tubing. The biased arm rides against the inner tubing wall until the body member is lowered out of the tubing when the positioning arm projects outwardly orienting the perforator in the desired direction until it reaches the perfoating depth.

The nature and objects of the present invention having been completely described and illustrated, what I wish to claim as new and useful and secure by Letters Patent is:

1. A perforator which comprises an elongated body member adapted to be lowered through a rst pipe in a casing to a position adjacent a second pipe extending below said irst pipe in said casing, said body member being free of any connection with said pipes, said pipes being arranged eccentrically in said casing, perforating means carried by said body member, a positioning arm pivotally mounted on said body member having a length greater than the greatest distance'between the second pipe and the inner wall of the casing, means urging said arm from a retracted position into a fully extended position, said urging means being of suicient strength to position the body member into contact with said casing, means for operating said perforating means only when said arm is fully extended, means carried by said positioning arm for actuating said operating means, said arm being maintained on said body member in said retracted position until said body member is lowered out of said iirst pipe, said perforating means being carried by said body member relative to said positioning arm such that on extending said positioning arm the perforating means is oriented on slidable contact of the positioning arm with the second .pipe to perforate said casing without perforating the second pipe.

2. A perforator in accordance with claim 1 in which the perforating means ina bullet gun.

3. A perforator in accordance with claim l in which the perforating means is a shaped charge.

4, A perforator in accordance with claim l in which the operating means is a `switch in an electrical circuit connected to a source of electrical energy for ring said perforating means and the actuating means is a trigger for operating said switch.

5. A perforator in accordance with claim l in which the arm is maintained in retracted position by a releasable means on said body member.

6. A perforator which comprises an elongated body member adapted to be lowered through a rst pipe in a casing to a position adjacent a second pipe extending below said first pipe in said casing, said body member being free of any connection with said pipes, said pipes being arranged eccentrically in said casing, perforating e means carried by said body member, a positioning arm pivotally mounted on said body member having a length greater than the greatest distance between the second pipe and the inner wall of the casing, means urging said arm from a retracted position into a fully extended posi-. Y

tion, said urging means being of sutlicient strength to position the body member into contact with said casing, said arm being maintained on said body member in said retracted position until said body member is lowered out of said rst pipe, said perforating means being carried by said body member relative to said positioning arm such that on extending said positioning arm the perforating means is oriented on slidable contact with the second pipe to perforate said casing without perforating the second pipe, and means for operating said perforating means responsive to extension of said arm from Ysaid body member when said body member and arm are in casing contact.

7. A perforator which comprises an elongated cylindrical body member adapted to be lowered through a iirst pipe in a casing to a position adjacent a second pipe extending below said rst pipe in said casing, said' body member being free of any connection with said pipes, said pipes being arranged eccentrically in said casing, perforating means carried by said body member, a positioning arm pivotally mounted on said body member having a length greater than the greatest distance between the second pipe and the inner wall of the'casing, spring means urging said arm from a retracted position into a fully extended position, and frangible releasable means on said body member for maintaining said arm on said body member in said retracted position, said spring means being of suflicient strength to position the body member. into contact with said casing, said perforating means being carried by said body member opposite said positioning arm such that on extending said positioning arm the perforating means is oriented on slidable lcontact of the positioning'arm with the second pipe to perforate said casing without perforating the second pipe, and means for operating said perforating means responsive to extension of said arm from said body member when said body member and arm are in casing contact.

8. A perforator which comprises an elongated cylindrical body member adapted to be lowered through a nrst pipe in a casing to a position adjacent a second pipe extending below said first pipe in said casing, said body member being free of any connection with said pipes, said pipes being arranged eccentrically in said casing,

shaped charge perforating means carried by said body` member, a positioning arm pivotally mounted on said body member having a length greater than the greatest distance between the second pipe and the inner wall of the casing, spring means urging said arm from a retracted positioninto a fully extended position, said spring means being of suticient strength to position the perforating means into contact with said casing, and frangible releasable means bearing against said arm for maintaining said arm on said body member in said retracted position, said perforating means being carried by said body member opposite said positioning arm such that on extending said positioning arm the perforating means is oriented on slidable contact of the positioning arm with the second pipe to perforate said casing without perforating the second pipe, and means for operating said perforating means responsive to extension of said arm from said body member when said body member and arm are in casing contact.

9. A perforator which comprises an elongated cylindrical body member adapted to be lowered through a first pipe in a casing to a position adjacent a second pipe extending below said rst pipe in said casing, said body member being free of any connection with said pipes, said pipes being arranged eccentrically in said casing, shaped charge perforating means carried by said body member, a positioning arm pivotally mounted on said body member having a length greater than the greatest distance between the second pipe and the inner wall of the casing, spring means bearing against said arm and said body member urging said arm from a retracted position into a fully extended position, .an electrical circuit connected to a source of electrical energy and to said shaped charge for tiring said shaped charge, a switch in said circuit, a trigger on said positioning arm operatively engaging said switch only when said positioning arm is fully extended, and explosive releasable means connected to said body member and bearing against said arm for maintaining said arm on said body member in said retracted position, said perforating means being carried by said body member opposite said positioning arm such that on extending said positioning arm the perforating means is oriented on slidable contact of the positioning arm with the second pipe to perforate said casing without perforating the second pipe.

References Cited in the le of this patent UNITED STATES PATENTS .2,616,370 Foster Nov. 4, 1952 2,644,519 Kanady Iuly 7, 1953 2,785,754 True Mar. 19, 1957 2,796,623 Abendroth .Tune 18, 1957 2,917,280 Castel Dec. 15, 1959 2,952,319 Popham Sept. 13, 1960 

